1. Field of the Invention
The present invention relates to a variable-volume receptacle, especially for use as a compensating receptacle in building heating systems; the receptacle is made in the form of a flat bag or bladder of two flexible sheets of rubber or synthetic material which are disposed against one another and are sealingly interconnected at their edges.
2. Description of the Prior Art
Up to now, in order to manufacture such a receptacle, it was customary to wrap one of the sheets, which was cut oversize, about the edges of the other sheet and to fold it down onto this other sheet in an overlapping connection, whereupon the peripheral contact zone is secured by being glued or vulcanized together. Despite the apparent simplicity of this method, a relatively high expenditure of work was connected therewith. Furthermore, the constantly present danger of defects or failures of the connection developing at a given location was the unavoidable basis for the rejection or scrapping of a certain proportion of receptacles produced pursuant to this heretofore known method. In addition, this type of connection of the edges was not able to sufficiently cope with the constantly changing buckling and bending stresses during use of the receptacle. The reason for this is that, independent of the quality of the adhesion zone, jagged tears surprisingly occurred repeatedly right in the curved portion of the overlapping larger sheet. Due to later fatigue failure, these tears lead to premature failure of the affected receptacle.
It is an object of the present invention, via a novel construction of the connecting area, to make possible a simplified manufacture of bladder-like, variable-volume receptacles while extensively eliminating otherwise imminent sources of failure, and furthermore, to greatly increase the service life and durability of the receptacle.